1. Field of the Invention
The present invention generally relates to motion estimation in an image processing system and, more particularly, to motion estimation and bandwidth reduction in a memory device
2. Description of the Related Art
Motion estimation is the process of looking for the best motion vector that minimizes the prediction errors. Prediction error is defined as the difference between the current macroblock (MB) and the prediction MB. In MPEG (Moving Picture Experts Group) codec design, motion estimation demands large DRAM (dynamic random access memory) bandwidth. This is because a great deal of data must be transferred from the DRAM to the processors for achieving motion estimation. MPEG is the committee that developed international standards (such as MPEG-1, MPEG-2 and MPEG-4) that made interactive video on CD-Rom and digital TV possible.
In general, a frame is formed by a large amount of pixels generally including 8 bits, 16 bits, or 32 bits. For a frame with a size of 640×480 pixels where each pixel has 8 bits, there are a total 640×480×8 bits in the frame. If the image should be displayed with a rate of 60 frames per second, then there are 640×480×8×60 bits (about 147 Mbits) of data to be displayed in one second. Since calculation of motion estimation is related to frames of different time periods and an algorithm provided must contain several operation steps, the amount of calculation required in processing the image data is very great. If the bandwidth of the DRAM is not sufficient, the calculation of the motion estimation will be delayed due to insufficient provision of the frame data, thereby causing the display speed of video image to slow down significantly. There is an optional thus a general need in the act for motion estimation method and device advantageously overcoming the aforementioned shortcomings in the art. In particular, a need exists in the art for an optional method and device, for motion estimation and bandwidth reduction in a memory device where the amount of calculations is greatly reduced and the bandwidth of the memory device is significantly reduced in optionally providing motion estimation.